This project proposes to study mitochondrial function in the fungus Neurospora crassa using mutants that are defective in mitochondrial energy transduction. Mutants are presently available that are defective in electron transport, ATP synthetase activity and in energy coupling. The electron transport mutants are defective in succinic dehydrogenase activity or are resistant to antimycin A. The ATP synthetase mutants are resistant to oligomycin and the energy coupling mutants are resistant to carbonyl cyanide-m-chlorophenyl hydrazone. Biochemical studies are proposed to purify and identify the structural genes products for succinic dehydrogenase, the antimycin A-binding protein the oligomycin binding protein, and the uncoupler binding protein. These mutants are then to be used to probe the mechanism of energy transduction in Neurospora.